Stretcher strain remover



N0v.'3, 1936. A. F. HANSON STRETCHER STRAIN REMOVER v Filed May 12, 1932 PIG] INVENTOR AQTHUQ P. HANSON BY ya ATTORNEY Patented Nov. 3, 1936 UNITED STATES PATENT OFFICE STBETCHER STRAIN REMOVED Arthur F. Hanson, Philadelphia, Pa., assignor to Edward G.

Budd Manufacturing Company,

Philadelphia, Pa, a corporation of Pennsylvania Application May 12, 1932, Serial No. 610,834

6 Claims. (Cl. 153-54) l sheet metal of such structures as automobile bodies, wherein these blemishes would cause unsightly and offensive highlights due to reflection thereupon, it is vitally important to prevent their formation if possible.

1 I have found that by cold working the sheets by bending and reverse bending by means of bends of relatively small radius, I am ableto stretch the sheets beyond their normal elastic limit and leave them in a state of what may be termed cold plasticity. It is found that when sheets have been treated in this manner previous to die forming operations, the objectionable wormy metal does not develop.

My invention has for its object more especially the construction of a machine adapted to cold-work sheet metal in such a manner that stretcher strains or wormy metal will not develop after forming or die drawing operations have been performed upon the sheets.

Another feature of this invention is to design the machine in such a fashion that substantially the entire sheet will be cold-worked by the passage through the machine.

I attain the above enumerated desirable objects and others incidental thereto by constructing a metal working machine including in combination a plurality of intermeshing sheet working members.

This invention will be better understood from the following description when considered in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

In the accompanying drawing wherein like ordinals represent the corresponding parts in the figures,

Figure 1 is a sectional side elevation of my niachine.

Figure 2 is a cross section of my machine taken upon the line 2-2 of Figure l.

It has been customary in the metal working art to construct machines commonly known as roller levelers, which are adapted for straightening the sheets prior to die forming or other operations. These machines, however, are not susceptible of eliminating stretcher strains in that if the working of the sheets is upon a sufficiently small 'radius to eliminate stretcher strains, the result will be that the sheet contains a substantial curvature and would not pass through the rolls. It is for the purpose of eliminating this curvature 5 that the roller leveler is used whereas a machine of the present type which may be termed a stretcher strain remover or preventer, cold works the sheet beyond its elastic limit adapting it much more readily to the uses of the roller leveler 10 in fact it combines these two operations into one machine. For purposes of illustration, I have shown a single embodiment of my machine,

however, other slightly modified constructions will be readily apparent. In Figure 1 I have 15 shown the sheet to be worked It, passing from left to right in the directiomof the arrow at the right hand extremity of the sheet. At the left of the figure I have mounted upon suitable sup porting members which are not shown, a group of opposed guide pinch or draft rolls It and II.

At the right hand side of the sheet working members I have mounted another set of similar rolls I 2 and it. These rolls may or may not be pinch rolls depending entirely upon the working 0011'? g; ditions as under some circumstances, mere guiding may be needed whereas again these rolls might be dispensed with entirely. Interposed between these rolls are mounted the sheet working members A and B. The drawing herein is 30 schematic and the parts are exaggerated with respect to each other merely for purposes of explaining the operation of my device without going into all of the minute details concerning bearing mountings, gear connections between the 35 various parts, and mechanism for controllingautomatically the operation of the separate parts. The pinch rolls are arranged in groups il-il and l2-l3 and the rolls of .eachgroup or set are adapted for opposite rotation with respect I to each other whereas, the corresponding rolls of the groups such as It and I! or II and it are adapted for the same direction of rotation. The roll groups may be termed leading or trailin with respect to the feeding of the sheets or any 45 other suitable designation may be used the only question of terminology being one of adequate description. If it is desirable to maintain the sheet in a condition of tension during the passage through the mschine, the leading rolls Ill and I I may be driven at a slightly diiferent speed from the trailing rolls l2 and It, for instance, the peripheral speed of the leading rolls may be feet per minute and the peripheral speed of the trailing rolls befeet per minute. The

result of this difference between these two peripheral speeds would be that a tension upon the sheet l4 would be maintained.

The sheet working members, generally designated as A and B, may comprise any one of a number of structures suitable for the needs of this invention. I have shown the device as comprising intermeshing dual groups of axially elongated sheet working rolls l5 having backing rolls l6, positioned interiorly of the sheet working rolls and concentrically of the circle described by the individual sheet working roll centers during operation. The sheet working rolls or tooth rolls as I have sometimes called them, are in the nature of the teeth upon a gear and it is by means of the passage of the sheet member M between the. intermeshed tooth members of the two rolls that I attain the essential working of the sheet. Naturally an expedient which would immediately come to the mind of a person skilled in this art, would be to replace by a gear type roll the type of roll which I have illustrated. Such a roll would clearly be within the scope of my invention and I intend to cover by the hereto appended claims this obvious way of accomplishing the same result, then again one of the rolls may be constructed of hard rubber or some other yielding substance in such a manner that the sheet working would occur due to the intermeshing action of the member B with the yieldable surface of the roll A. The construction illustrated more admirably meets the conditions in practice and for the description it is used. As the pinch rolls are well known in the art of roller levelers, no further description thereof is deemed essential and I will limit the description entirely to the sheet working members.

The sheet working or tooth rolls ii are mounted in bearings carried by the substantially gear shaped members I! which are made in this form to allow free passage of the roll members through the axis 2-2 without any mechanical interference. The gear form is readily apparent at I8 in the various figures. These members I! are provided with a. central axis IS, in the form of a drive shaft supporting the members I! and keyed at 20 to the shaft so that a drive from some suitable power source may be obtained. Interiorly of these rolls and concentrically of a group axis is mounted the backing roll i6 upon bearings 2| allowing free rotation of this roll with respect to the tooth rolls and also with respect to the drive shaft IS. The purpose of this roll is essentially that which its name implies, namely;a firm backing or base for operations. It is apparent that if this procedure is used with sheet metal sufliciently thin in nature, the backing roll might not be necessary, likewise if the sheets were of relatively slight width this may be possible. However, in operating upon sheets of substantial width, such a construction is highly desirable.

For purposes of maintaining the two sheet working members in aligned and operative intermeshing relation the supporting end members 22 are used. These members are secured to the main frame of the machine and they carry the ferent machine used. It is for purposes of this relative adjustment that the bearings of this type are shown. Any other suitable mechanism can be used inasmuch as simple adjustment is the desirable feature. The individual tooth rolls or metal working rolls l5 are freely rotatable within bearings 25 and are likewise freely rotatable with respect to the backing roll Hi. However, by properly constructing the machine the peripheries of the tooth rolls and the backing roll'are co-extensive upon a medial line connecting their individual centers.

For what may be termed a normal operation of the machine the dual intermeshing groups of sheet working rolls are given the same direction of rotation as the tensioning rolls. However, if it is desirable that the sheet working groups be relatively reversable in direction of rotation with respect to the tensioning rolls, possibly under some circumstances to prevent a piling up of the sheet l4 after its trailing edge has left the leading rolls l0 and II, this may be obtained by some suitable gear arrangement in the nature of that disclosed.

The shafts I9 are normally driven from some power source not shown, which may be an electric motor or any other device connected for instance by means of a belt 30 driving the shaft 3|. This may be a direct drive and the belt be unnecessary under those circumstances. Shaft 3| is mounted in bearings 29 and secured to the machine frame. Splined upon the shaft 3| are dual groups of miter gears 32 and 33. These gears intermesh with the gears 34 upon the shafts l9 completing the driving connection from the power source. The drive for one direction of rotation would be from the power source through the shaft 8| to the respective gears 32 and thence through the gear 34 to the shaft l9. However, if the direction of rotation of the sheet working rolls is to be reversed relatively to the pinch rolls, this may be obtained by means of a simple mechanism comprising a member 35 carrying plural eccentric grooves 36 which receive pins 31 mounted in the collars of the gears 33. By a rotary motion of the member 35, the pins are moved apart, thus disengaging the gears 32 and 34. Further movement meshes the gears 33 and 34. This mechanism is merely for purposes of explanation and any suitable arrangement to obtain the result desired is comparable to that disclosed.

The operation of my machine is essentially as follows. The sheet I4 is fed into the leading pinch rolls l0 and II which continue to feed it into the intermeshing groups A and B. when the sheet has passed between the particular rolls 40 and 4| it begins to receive a bending action between the rolls 4| and 42. This bending continues until the sheet reaches the roll 42 at which time a reverse bend is obtained. The passage of the sheet continues through the rolls and thence between the rolls I 2 and I3 until the entire sheet surface has been worked. It is readily apparent that should it be desirable to impart still additional bending to the sheet, the pinch rolls might be adapted for vertical positioning with respect to their indicated position so that an additional bend of the sheet might be obtained. This is a mere matter of expedients. however, and further discussion thereof is not thought desirable. If any possibility of piling up of the sheets within the sheet working rolls should occur or be found to occur. the working rolls A and B can be reversed in direction of rotation relatively with respect to the pinch rolls by means of the mechanism shown. Such a reversal could take place at any time after the trout edge of the sheet was engaged by the pinch rolls i2 and IS the progress oi. the sheet being in the same direction, but upon resumption of the motion the tooth rolls being in a reversed direction.

A peripheral speed of the various rolls should approximate the linear speed of the sheet through the machine whereby it is possible to make the tooth rolls oi relatively small diameter, but the various speeds should be co-ordinated in such a manner that scumng oi the sheets will not occur. The peripheral speed of the rolls might possibly exceed the speed of the sheet but it would he commensurately related to the ratio between the driven speed and the speed of the sheet in such a manner that there would not he occanoned any drug of the surface of the tooth rolls. The reverse action of this mechanism is normally unnecessary, but it is incorporated in the machine at the time of construction when relatively slight additional cost supplies this additional service for purposes which may occur at later times.

The embodiment of the invention illustrated and described has been selected for the purpose of clearly setting forth the principles involved. It is apparent, however, that it is susceptible of being modified to meet the dlfierent conditions encountered in its use and I therefore aim to cover by the appended claims all modifications within the true spirit and scope of my invention.

I claim as my invention:

1. In a stretcher strain remover the combina-' tion of leading and trailing sets of pinch rolls, dual intermeshing groups of axially elongated tooth rolls, hacking rolls positioned interiorly of said groups and concentrically of the circle described by the individual tooth roll centers dur- .ing operation, said backing rolls adapted for relatlve reverse direction of rotation with respect to said pinch rolls and means adapted to adjust said groups between centers.

2. In a stretcher strain over the combination of leading and trailing sets of pinch rolls, dual intermeshing groups oi axially elongated tooth rolls interposed between said sets oi pinch rolls, and backing rolls positioned interiorly of said tooth rolls concentrically oi the circle described by the individual tooth roll centers during operation, and means adapted to relatively adjust said backing rolls between centers.

- 3. In a metal working machine the combination 01 intermeshing sheet "working members comprising concentrically mounted dual groups of axially elongated and synchronously driven roll members and hacking rolls concentric with said group roll centers.

4. In a machine for cold working sheet metal material the combination of dual inter-meshing groups of axially elongated rolls, and backing rolls positioned interiorly of said groups and concentrically oi the circle described by the individual group roll centers during operation.

5. in. a machine for cold workinasheet metal to prevent stretcher strains, the combination of leading and trailing sets of draft rolls, dual intermeshing sheet working rollsinterposed between said sets of draft rolls, and means adapted to relatively reverse the direction of rotation of said sheet working rolls with respect to said drait rolls.

6. In a stretcher strain remover the combination of leading and trailing groups oi tensioning rolls, dual lntermeshing groups of axially elonsated sheet working rolls the individual roll centers of each group describing a circle concentric with the groupaxis, hacmng rolls interposed with- 

